The invention provides a system and method for performing channel-associated signaling backhaul of non-ISDN formatted signals in an open network gateway routing system.
Due to the convergence of data and voice networks in today""s advanced telecommunications industry, open network gateway (ONG) routing systems must provide processing (also known as xe2x80x9cswitchingxe2x80x9d) of a variety of call signals. However, the desire to increase routing system throughput while reducing complexity continues to drive companies toward efficiency and scalability.
In the past, telephony switches and routing systems were designed as monolithic systems that became very expensive as they were scaled to handle large numbers of connections. However, as the evolution of network technology increases in pace, the cost of such systems can no longer be amortized over long periods of time, and rapid upgrades in performance and functionality are required for operators to remain competitive. In addition, operators are now more reluctant to tie their fortunes to a single vendor and prefer system architectures that are modular and based on open protocols and standards.
Organizations such as the Internet Engineering Task Force (IETF), the International Telecommunications Union (ITU), Multiservice Switching Forum (MSF), and the International Softswitch Consortium (ISC) have begun to develop architectures and protocols that address these needs. These developments come at a time of converging voice and data networks and growing demand for larger and more sophisticated routing systems, such as open network gateways that can adapt various forms of media for transport over IP networks.
Signaling System No. 7 (SS7) is the preferred signaling protocol for call management in large, digital networks because of its efficiency, scalability, and supported features. SS7 provides an architecture for performing out-of-band signaling in support of the call-establishment, billing, routing, and information-exchange functions of the public switched telephone network (PSTN). In service areas where SS7 signaling is not available, most ONG routing systems are capable of processing Integrated Services Digital Network (ISDN) signals with little difficulty, due to the compatibility of signal software protocols associated with the ONG system. However, in less-developed areas of the world that continue to employ analog technology, ISDN signaling may also be unavailable. Instead, these public switched telephone networks use channel-associated signaling (CAS), which is not easily integrated with ONG software protocols.
Currently, routing systems, such as network access systems (NAS), are being used in networks that employ a variety of call management signaling. Such systems typically include embedded hardware and software modules that implement complex algorithms used to identify, route, and process call signals. These routing systems must support the totality of signaling protocols used throughout the market area or must be manufactured and/or configured to support the unique requirements of particular submarkets. In addition, the processing of complex call signals often consumes valuable resources that degrade the overall performance of the routing system. The complexity of network access systems and similar devices greatly increases the associated development, manufacturing, and maintenance costs. What is needed is a way to reduce the complexity of a routing system.
As the demand placed on an individual network grows, additional capacity must be added. For example, as our economy and society become more connected, network access nodes must be added to accommodate the increase in traffic, as well as an expanding customer base. However, monolithic routing systems do not scale well because each additional access node replicates the complex call signaling subsystems embedded within them. Although traffic handling may be enhanced via distribution across multiple systems, call management is often adversely affected due to its centralized nature and need to access common databases. There is a need in the art for a way to easily scale the configuration of routing systems.
Many different types of call signaling protocols are used throughout the world. Even when a common protocol is used throughout a wide geographical area, different countries and regions often use national variations that must be certified by accredited organizations. SS7 signaling is used in most developed nations and is the preferred protocol implemented by open network gateway (ONG) systems. Such systems are typically optimized to use SS7 signaling. Where SS7 is not used, increased overhead results in slower processing, thus degrading ONG system throughput. There is a need in the art for a way to provide an ONG system to networks that do not have dedicated SS7 signaling.
The invention relates to a method of channel-associated signaling backhaul. The method generally includes the step of receiving communication data over a first communication link. The method further includes the step of determining whether the received communication data supports SS7 signaling. The step of determining whether the received communication data supports SS7 signaling further includes identifying the presence of CAS signaling protocol identifiers in a media channel or associated subchannel. Where received communication data does not support SS7 signaling, the method further includes accomplishing a set of steps of transmitting a setup message to a DMS1 service interface and converting DMS1 signals to Q.931 messages and backhauling such messages to a signaling station. In one embodiment the Q.931 messages are compatible with an ISDN Q.921 user adaptation layer.
The step of receiving communication data over a first communication link may be accomplished by a Public Switched Telephone Network line supervision driver. Additionally, the step of receiving communication data over a first communication link includes monitoring and controlling ABCD signaling bits accessed via a second T1 framer in accordance with a provisioned line supervision procedure.
In another embodiment, the step of receiving communication data over a first communication link may include receiving a SETUP_IND signal. The step of receiving communication data over a first communication link further includes proceeding in accordance with a provisioned address registration procedure. Additionally, if a DSP resource is required for tone detection and generation, the step of receiving communication data over a first communication link further includes allocating such DSP resource.
In another embodiment, the step of receiving communication data over a first communication link includes the step of receiving a SETUP_CONF signal. The step of receiving communication data over a first communication link further includes acknowledging the line seizure by generating a wink-start or delay-dial signal on a second T1 line. Additionally, if dial pulse registration has been provisioned, PSTN line supervision driver monitors ABCD signaling and reports address digits to PSTN DM using INFO_IND signals.
If tone registration has been provisioned, the method of channel-associated signaling backhaul may include the steps of detecting DTMF tones. Additionally, if tone registration has been provisioned, the method of channel-associated signaling backhaul includes collecting address digits in accordance with a provisioned number plan. Furthermore, when the address information is complete, the method includes the step of signaling SETUP_IND to DMS1 service interface, constructing a SETUP message, and passing called and calling numbers enbloc to a user adaptation layer.
The step of accomplishing a set of steps of transmitting a setup message to a DMS1 service interface and converting DMS1 signals to Q.931 messages and backhauling such messages to a signaling station is accomplished by providing conversion services between a DMS1 service interface and Q.921 service interface. Additionally, this step includes receiving DMS1 signals, converting said signals to Q.931 messages, and passing said messages to a Q.921 user adaptation layer in the form of a DL_DATA_IND event. Furthermore, this step includes converting Q.931 messages received from Q.921 user adaptation layer as DL_DATA_REQ events to DMS1 events and signaling such messages to PSTN DM.
In another embodiment, the step of accomplishing a set of steps of transmitting a setup message to a DMS1 service interface and converting DMS1 signals to Q.931 messages and backhauling such messages to a signaling station is accomplished by PSTN DM. This step includes waiting for DMS1_PROCEED_REQ, DMS1_ALERTING_REQ, and DMS1_CONNECT_REQ signals from Q.921 user adaptation layer via the DMS1 service interface. This step further includes generating call progress tones as necessary, and when the DMS1_CONNECT_REQ signal is received, PSTN DM releases DSP resources and signals call acceptance to the PSTN line supervision driver.
In another embodiment, the step of accomplishing a set of steps of transmitting a setup message to a DMS1 service interface and converting DMS1 signals to Q.931 messages and backhauling such messages to a signaling station is accomplished by signaling completion of call connection via a DMS1 service interface with a DMS1_CONNECT_CONF event which is converted to a Q.931 CONNECT ACKNOWLEDGE message and forwarded to a Q.921 user adaptation layer.
The invention can also be expressed as relating to a data communication system for handling a plurality of signal protocols. The data communication system includes a routing system connected to a first communication network and a second communication network. The routing system is comprised of a media gateway system for setup and teardown of media connections. The routing system is further comprised of an ISDN signaling gateway for generating associated SS7 signals from CAS data. The data communication system further includes an SS7 signaling gateway for interpretation and/or termination of SS7 signals. Additionally, the data communication system includes a first SS7 communication link connecting the SS7 signaling gateway with said first communication network, said first SS7 communication link used for communicating SS7 signaling messages with said first communication network. Finally, the data communication system includes a second SS7 communication link connecting the SS7 signaling gateway with the routing system, where the second SS7 communication link used for communicating SS7 signaling messages generated from the ISDN signaling gateway of the routing system with the SS7 signaling gateway.
In one embodiment of the data communication system, a Public Switched Telephone Network DM operates in concert with hardware and firmware subsystems to implement and manage Public Switched Telephone Network CAS signaling protocols. Additionally, the Public Switched Telephone Network interface connecting the routing system to the communication networks may include a Public Switched Telephone Network line supervision driver as a firmware module that manages supervisory signaling and communicates with Public Switched Telephone Network DM via a communication bus. Furthermore, the Public Switched Telephone Network interface connecting the routing system to the communication networks may include a Public Switched Telephone Network line supervision driver that interfaces directly with a second T1 framer to monitor and manipulate line supervisory signals.
In another embodiment, the data communication system is configured to support one or more line engagement procedures selected from the group consisting of immediate start, wink start, and delay-dial delay start.
In another embodiment, the data communication system is configured to operate such that once a line is seized, a Public Switched Telephone Network DM commences with register signaling through the detection and generation of dual tone multi-frequency tones in the media stream. Furthermore, generation of dual tone multi-frequency tones in the media stream includes the steps of requesting a DSP resource requested from DSPRM via an IPC link, as required, and connecting to the dial endpoint by SMS through an exchange of primitives via the IPC link. Additionally, the call progress signals may also be generated using the same DSP. In another embodiment, within the routing system connecting the data communication system with the communication networks, the Public Switched Telephone Network interface uses call control primitives supported by Integrated Services Digital Network DM.
In another embodiment, the data communication system comprises a Call Manager that operates independently of the type of signaling being performed by Integrated Services Digital Network DM and Public Switched Telephone Network DM. In yet another embodiment, the data communication system is configured to restrict network signaling dependencies to the corresponding dial managers.